A coffee cherry 100 comprises, as illustrated in a sectional view of FIG. 4, outermost pericarp 101, inside parchment 102, pulp 103 filling the portion between the pericarp 101 and the parchment 102, silver skin 104 inside the parchment 102, and seed wrapped in the silver skin 104, that is, what is called coffee bean 105. In this specification, it is noted that, so far as there is no possibility of causing misunderstanding, the term "coffee bean" may be used extensively in some cases, inclusive of the one which has the silver skin 104 on the surface of the coffee bean 105.
The coffee cherry 100 having the above structure is processed, after being reaped, through the procedure shown in a flow chart of FIG. 8.
First, the reaped cherries 100 are immersed in water in a tank 110, and only the cherries 100a sunk to the bottom of the tank 110 are taken out, so that only the cherries 100a having the mature seeds 105 are obtained Subsequently, the cherries 100a thus obtained are put into a pulp removing machine 112 so that the pericarp 101 and the pulp 103 are removed from each of the cherries 100a which are then immersed again in water in a tank 104 so that the pulp 103 and the like floating on the water is washed away.
Raw or green coffee beans 105a thus obtained are fermented by a fermentation device 114. The fermentation by the fermentation device 114 is continued for 12 to 18 hours at high temperature or 30 to 40 hours at low temperature. Raw coffee beans 105b after the subjection to the fermentation process are washed in water while being stirred up, and then dried by a drying means 116 in a drying field, thus obtaining parchment coffee beans 105c each having the parchment 102 wrapped thereon. Drying of the coffee beans 105 is effected in the sun in the drying field or in a drying machine by heating with an artificial heating device.
The parchment coffee beans 105c are further subjected, in the drying field, an export port or an importing country, to a separation process by a roll machine 118 so that the parchment 102 is removed from each coffee bean real body 105 and sifted out through a screen.
Further, green or raw coffee beans 105d thus obtained are further put into a color sorting machine 120 in some cases so as to separate and remove the inferior raw coffee beans the color of which is changed due to must, damages by blight and harmful insects, rot or immaturity, from the raw coffee beans 105e of good quality in accordance with the difference in color.
However, the raw coffee beans 105d obtained through the separation process by the roll machine 118 often contain the one that the silver skin 104 remains partially on the outer surface of the coffee bean real body 105 as shown in FIG. 5. Further, since the silver skin 104 is rolled into a center cut portion 106 of the coffee bean real body 105, it often remains as it is.
As a result, there has been a possibility that, in roasting by a roasting apparatus 122, the silver skin 104 is burnt to generate a bad smell which soaks into the roasted bean 105f.
In addition, in sorting the coffee beans 105d by the color sorting machine 120, it has been hard to prevent the raw coffee beans 105e of good or normal quality from being removed as inferior beans only due to the existence of the remaining silver skin 104 described above.